ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02376.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThe present study examined modification of the startle reflex in psychosis‐prone and normal control subjects, using a continuous pure tone prestimulus (S1) and an intense white noise startle stimulus (S2). Reflex modification conditions consisted of stimulus pairs with onset asynchronies of 60, 120, and 2000 ms with a startle‐alone condition as control. Startle was indexed by the eyeblink, which was measured by vertical electro‐oculography. Subjects were identified as psychosis‐prone by their high scores on the Perceptual Aberration or the Physical Anhedonia scales.Group differences in blink magnitude inhibition were observed between perceptual aberration and control subjects during short stimulus onset asynchronies, with perceptual aberrators showing significantly less inhibition than controls at 120 ms. No differences were evident between anhedonic and control subjects at the two short onset asynchronies nor were there any significant between‐group differences when the interval between stimuli was long (2000 ms). These results suggest that subjects with perceptual aberrations may share with schizophrenics and other schizophrenia‐spectrum subjects an underdeveloped mechanism which in normal subjects is presumed to operate during preattentive processing and functions to protect sensory information from the interfering effects of subsequ

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02004.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02005.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThis paper describes efforts to reduce measurement error in the assessment of cardiovascular reactivity by standardizing task requirements and by aggregating data across tasks and testing sessions. Using these methods, reliable measures of reactivity (.80 or greater) were obtained on five different measures of cardiovascular function (heart rate, systolic blood pressure, diastolic blood pressure, stroke volume, pre‐ejection period) in samples of college students and community volunteers. Methodological limitations may have hampered previous efforts in this area. Current findings are consistent with a dispositional model of cardiovascular reactivity, and they suggest productive future strategies for obtaining reliable assessment

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02006.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTEvent‐related potentials (ERPs) were recorded during a task requiring continuous recognition memory for visually‐presented words. Twelve subjects each performed the task twice, once following the administration of scopolamine, and once after receiving a saline placebo. In the placebo condition, correctly detected “old” words (i.e., words that had been presented once before during the task) evoked more positive‐going ERPs than did “new” words. Scopolamine caused a substantial impairment in task performance, but did not reduce the size of these old‐word/new‐word ERP differences. It is concluded that old/new ERP effects are unlikely to reflect cholinergically‐mediated neural activity underlying normal

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02007.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02008.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThis study explored age differences in the N400 component, described by Kutas and Hillyard as an index of semantic expectancy. A group of young students and a group of middle‐aged academics read a number of congruent and incongruent sentences followed by a recognition task. Age differences were found in both accuracy and speed in the recognition task. The N400 elicited in the reading task was both delayed in latency and reduced in amplitude in the older group. These aging effects could not be attributed to early stimulus input processes because the N1 did not differ between the age groups. A re‐averaging of the event‐related potentials during reading as a function of subsequent recognition showed a small memory‐related positivity for the younger group and a large memory‐related positivity for the older group, suggesting a difference in the encoding strategies of the two groups. To check the generalizability of the results of this particular age group, a further task (a memory scanning task) was carried out. The results, a delayed P3b and an increased reaction time, matched those found in the l

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02009.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02010.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

ABSTRACTThe spectral analysis of time series requires the signal to be at least weakly statonary; i.e., the mean, (co‐) variance, and spectrum of the time series should not vary from segment to segment. It is commonly assumed that psychophysiological time series are not stationary. This study introduces a nonstationarity test to the psychophysiological literature, which is derived from evolutionary spectral analysis. Basically, the test consists of a double window technique in both the time and frequency domains, leading to a two‐way analysis of variance for times and frequencies. In the current study, the nonstationarity test is applied to heart rate data obtained in a typical psychophysiological setting. Heart rate and respiration were measured in four age groups under four conditions—rest, paced breathing, vigilance, and reaction time. The results indicate that only few physiological time series were completely stationary. However, for every subject, and in every condition stationary strectches could be found that were long enough to apply spectral analysis. Spectral measures (power, coherence, and phase spectra) were then compared for stationary parts of the data and the total data. This comparison indicated that nonstationarity affects all spectral measures. Most importantly, Stationarity × Task Condition × Frequency Band interactions were observed for coherence and phase spectra, and there were significant interactions with age for each of the spectral indices. These findings suggest that nonstationarity may result in biased outcomes of significance tests of the effects of task manipulations on the spectral indices of cardiac time series. Thus, it was concluded that the stationarity test should be routinely applied in the spectral analysis of physiological time series. In addition, it was suggested that the nonstationarity test has an even wider range of application that might be of interest to the psychophysi

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02011.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1992.tb02012.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY